Electrical Stimulation

How does electricity produce therapeutic effects?

depolarizes nerve membranes and produces action potentials

How many sodium ions exit the cell during resting potential?

3

How many potassium ions enter the cell during resting membrane potential?

2

The charge on the inside of the cell is slightly NEGATIVE/POSITIVE during resting membrane potential.

negative

The charge on the outside of the cell is slightly NEGATIVE/POSITIVE during resting membrane potential.

positive

What is the resting membrane potential value (mV)?

-70

What is the threshold value to start an action potential (mV)?

-55

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.

depolarization

period during which potassium ions diffuse out of the neuron

repolarization

a period of inactivity after a neuron has fired

refractory period

these types of nerve fibers have the lowest pulse duration in the strength-duration curve

A-beta sensory

these types of fibers have the longest pulse duration in the strength-duration curve

denervated muscle

Order of fibers from shortest to longest pulse duration in the strength-duration curve

A-beta sensory
Motor
A-gamma sharp pain
C dull pain
Denervated muscle

T/F: A-gamma sharp pain fibers have a shorter pulse duration than motor nerves.

false

T/F: C dull pain nerve fibers have a longer pulse-duration than A-gamma sharp pain fibers.

true

rheobase

the minimum current amplitude with very long pulse duration to produce an action potential

chronaxie

minimum duration it takes at twice rheobase to produce an action potential
usually considered the most comfortable setting for patients

Action potentials occur in ONE/BOTH direction(s) physiologically.

one

Action potentials occur in ONE/BOTH direction(s) if stimulated electrically.

both

NMES (neuromuscular electrical stimulation) is associated with what type of muscle

innervated muscle

EM (electrical muscular stimulation) is associated with what type of muscle

denervated muscle; higher amplitude

What muscle type is recruited first with electrical stimulation?

type II

Label A.

action potential

Label B.

isometric twitch

C and D are considered what?

Tetanus

neuropraxia

local nerve conduction block due to mild compressive forces
may involve local demyelination or the arm going to sleep

axonotmesis

axon and myeline sheath disintegrate but endoneurial sheath intact due to severe compression of nerve
example - spinal nerve root compression via herniated nucleus pulposus

neurotmesis

loss of axonal and connective tissue continuity due to stretch or severance of nerve

Wallerian degeneration

degeneration of the peripheral nerve, specifically the nodes of Ranvier

Denervation - Regeneration

Schwann cells proliferate
Growth tip (cone) forms
Axons elongate
Axon guided by Schwann cells to target muscle
Axon connects to target muscle

What is the daily rate of regeneration for nerves?

1-2 mm

What is the rate of generation of nerves in a month?

1 inch

electric charge

positive or negative charge

protons

positive charges

electrons

negative charges

electricity

difference in the number of electrons at two points

electromagnetic force

potential difference or voltage
magnitude of the attraction or driving force behind the electrons

current

electrons flowing in an attempt to equalize the difference in charges
the movement of charge particles through a conductor
flow will be in the pathway of least resistance

1 ampere = what

movement of 1 coulomb of charge past ay point in one second

Current flow in a battery moves from the POSITIVE/NEGATIVE pole to the POSITIVE/NEGATIVE pole.

negative, positive

cathode

negative pole of the battery
has high electron concentration

anode

positive pole of the battery
has low electron concentration

cation

positively charged particles

anion

negatively charged particles

voltage

change in electrical potential energy between 2 points
driving force that makes charged particles move, also referred to as the electromotive force of EMF

conductors

charged particles move readily

What are examples of good conductors within the body

biological tissues and Na+, K+, and Cl-

insulators

substances where there is limited movement of charged particles

What are examples of good insulators within the body

Skin and fat

direct current

galvanic
continuous, uninterrupted flow of electrons (1 second)

alternating current

sinusoidal
continuous or bidirectional flow of electrons
expressed n Hz or cycles per second

pulsed current

the flow of the current starts and stops
may be monophasic or biphasic, electrical current delivered discontinuously
periods of pulsing followed by periods where no current is flowing (usually off longer that it is on)
may be unidirectional or bidirectional

amplitude

magnitude of the current or intensity or strength
intensity - stimulus high enough to effect depolarization of membrane
measured in amperes and volts

frequency

RATE
number of cycles or pulses per second (pps)
measured in Hz

duration

consists of pulse and phase

pulse duration (red)

pulse width
may involve multiple phases

phase duration (black)

equal to pulse in monophasic wave forms

List 5 contraindications for electrical stimulation.

cardiac pacemaker
unstable arrhythmias
over carotid sinus
over arterial or venous thrombosis
pregnancy

List the 6 precautions for electrical stimulation.

cardiac disease
impaired mentation
impaired sensation
tumors
skin irritation
open wounds

iontophoresis current

anti-inflammatory is produced in a liquid form (typically dexamethasone)

Does dexamethasone have a slightly positive or negative charge?

negative

___cc placed on the electrode of the same charge for iontophoresis.

2

What are the typical parameters for iontophoresis (include intensity and duration)?

1-4 mA for 40 mA/min

iterferential current

1000-10,000 Hz
two circuits with 2 different carrier frequencies
beat frequency = carrier frequency 1 - carrier frequency 2
increased comfort
may stimulate wider and deeper area

premodulated current

single circuit, same waveform
used for topical/more superficial pain relief

Russian protocol

intended for quad recruitment

____ Hz frequency in 10 ms long burst for Russian protocol

2500

___ bursts per second with a 10 ms interburst interval for Russian protocol.

50

What are the two types of monophasic currents

Monophasic (MPC)
High volt (HVPC)

biphasic

symmetrical and asymmetrical (balanced and unbalanced)

Label C.

interpulse interval

Label D.

rise time

Label E.

decay time

peak amplitude

point of positive or negative maximum displacement during electrical stimulation

1000 Hz is considered LOW/MEDIUM/HIGH

low

1001-10000 Hz is considered LOW/MEDIUM/HIGH

medium

>10000 Hz is considered LOW/MEDIUM/HIGH

high

modulation

changes in current characteristics
burst of cycles/pulses

amplitude modulation

variations in peak amplitude of a series of pulses

pulse duration modulations

regular changes in time over which each pulse acts

frequency modulation

cyclic variations in the number of pulses applied per unit time

accomodation

the effect of modulation on adaptation

List the four dynamics of electrodes.

skin-electrode interface
electrode size and current density
distance between electrodes
electrode orientation

What type of electrical stimulation is depicted?

IFC

What type of electrical stimulation is depicted?

monophasic

motor point

site in nerve/muscle which is most easily excited producing a visible muscle response using a minimal level of electrical current

innervated motor point

muscle twitch (low rate) > tetanic contraction > fused tetanus (high rate)

denervated motor point

vermicular contraction

TENS acupuncture

limited utility in individuals with long-term opioid use and chronic caffeine intake
same binding site

Frequency 2-3

pulse duration and intensities should be changed at least every __-__ visits.

NMES

muscle contraction is visible

TENS

patient muscle be able to feel the stimulation

T/F: Electrical stimulation is best when using a multimodal approach.

true